For sweeping glass surfaces so as to obtain good visibility through them, it is known to use wipers which oscillate in alternating movement so as to sweep against the surface to be swept. Such wipers will be referred to herein for convenience as windshield wipers and are to be understood to comprise one or more wiper blades. Each wiper blade is usually driven through an appropriate articulation by a wiper arm which is itself driven in alternating rotational movement by an output spindle or shaft of a drive mechanism carried by the body of the vehicle. In known windshield wipers, the coupling between the output spindle of the drive mechanism and the wiper arm comprises a driving head which is part of the wiper arm and which is secured on the output spindle, usually by means of a nut.
An articulation or pivot, defining a pivot axis and generally comprising a rivet, is arranged between the driving head and the shroud of the wiper arm at the level of the driving head. A spring is interposed between the shroud and the driving head, so that during operation the spring urges the windshield wiper arm, with its blade, with a substantial pressure against the swept surface. The shroud is usually of a transverse cross section in the form of a U and encloses the spring between its two projecting side walls or wings. This spring may be arranged, in different embodiments, either as a compression spring or as a tension spring.
It is important that the windshield wiper arm can easily be replaced. To this end, it is currently necessary to move the arm away from the glass by pivoting it about the above mentioned pivot. After moving a protective cap, it is then necessary to unscrew the fastening nut which holds the driving head on the driving spindle, in order to replace the arm. This requires the use of a tool such as a key or spanner for unlocking the nut. Such a tool is not always available.
It has already been proposed, in the specification of French published patent application No. FR 2 103 349A, to provide a windshield wiper arm which is arranged on a drive spindle, in which the said arm has no driving head, but has a single pivot pin which is inserted into a groove provided in the drive spindle. The arm is retained on the spindle by means of a resilient member such as a band. This assembly renders it necessary to provide a machined recess in the drive spindle, and the latter has to be indexed with respect to the swept surface in order that the angle through which the wiper blade sweeps on the swept surface is correctly orientated.
In addition, such an assembly also has the drawback that the arm is not retained in a position fully spaced away from the swept surface, in view of the fact that in this position, the resilient member no longer engages on the shaft, and the pivot axis can be dislodged by the weight of the arm itself from the recess in which it is engaged.